Precoated material and dry lubricating coating composition therefor



Psama May 10, 1949 rnncos'rrn MATERIAL AND our warncame COATINGcoMrosmoN 'rnnan- FOB 'Roland A. Whitbeck, Lorain, Ohio, assignor toGllron Products Company, Cleveland, Ohio, a

corporation of Ohio No Drawing. Application October 8, 1948,

Serial No. 53,591

17 Claims. (Cl. 252-48) This invention relates to a new article ofmanufacture and to a new and improved combination lubricating andprotecting composition for metal bars, rods, and sheets, and to acomposition for forming such a coating thereon.

The present composition more particularly relates to the type oflubricant commonly referred to as dry lubricant and is applied in wetcondition to the metal stock'and caused, or permitted, to dry thereon,thereby forming on the stock a dry coating or film after which the drycoated stock is subjected to pressure die forming operations without theaddition of other lubricating and cooling agents.

For the purposes of illustration, the present invention is described asapplied in the deep drawing of sheet steel and steel alloys in pressuredies, for which it is particularly adapted, its application to thedrawing, stamping and shaping of other kinds of sheet and rod stockbeing apparent from the illustrative example.

Heretofore, blank steel stock for subsequent forming operations has beenshipped from the mill to the customer after the final cleaning at themill. However, it is desirable that the surface of the metal beprotected during shipment. Also it is desirable that, at the fabricationor forming site, the metal be lubricated properly at the time of use.Usually it is necessary to cleanse the metal at the fabricating orforming site just prior to use to remove foreign substances which haveaccumulated thereon during shipment.

It is necessary also to use a lubricant during fabrication and formingand such lubricant must be adapted for the particular type of operationto be performed on the metal.

The small manufacturer seldom has available the proper equipment forthese cleaning and lubricating operations and usually does not haveknowledge of the particular lubricant which should be used, the mannerof handling, the amount to be used, etc., particularly in those plantsof which most of the metal used is oronly from experts in the variousmetal and lubricating fields. The small company cannot afford suchadvice and small occasional orders do not justify the mill ininvestigating the specific problems of each small buyer.

The principal object of the present invention is to make available tothe small user the proper metal for his particular need in condition forhis use in the form in which it is received from the mill and to freehim from the burden of proper cleaning and lubricating of the metal.

A more specific object is to provide as an article of manufacture, blankstainless steel stock for subsequent forming operations which isprecoated with a permanent self-adherent dry film of material whichprotects the metal and lubricates it properly, whereby it may be formedefllciently by dies, presses and the like as received from the mill.

Another object is to provide a composition which is adapted to provide acoating of the character heretofore described.

Other objects and advantages will become apparent from the followingspecification.

After metal, particularly steel, stainless steel, and steel alloys, ismilled in accordance with known procedures, it is subjected to the finalsteps which usually include pickling and cleaning. Immediately followingthese final steps and while the surface of the metal is clean andbright, the metal is coated with a combined protective and lubricatingcoating, then, in the case of wire, rod-or band stock, is coiled, or, inthe case of sheet stock, is stacked.

The composition of the present invention comprises essentially borax andwater soluble high titre soap, preferably tallow or palm oil soap, or acombination thereof, and preferably having a melting point of from 36 to42.

The proportions of the ingredients of the dry mix which are the activelubricating ingredients of my invention are as follows, the percentagegiven being my weight:

Preferred Range Per cent Per cent Water-soluble high titre soap 15-2010-33 Borax 86-80 v 90 67 solution. is applied to the stock to be drawnin any suitable'manner such, for example, as by peratures and pressureswhereas an increase in the borax content provides better lubrication atthe higher pressures and temperatures.

n the other hand, an excess of soap over that required for a particulardraw may result in charring of the excess on the surfaces of the metalarticle and dies with well known disadvantages attendant upon such acondition. An excess of soap above the upper limit recited results in atacky coating or film having low or little adherence to the stock.

An excess of borax for a particular draw produces a film which is apt toflake off, or fail to operate properly in that the stock, because oflack of lubrication initially, becomes scored before a high enoughpressure and temperature are reached to render the borax fullyoperative.

An excess of borax above the upper limit recited results in coatingwhich is dusty, or causes a dusty condition in the dies, and which hasinsuificient plasticity and adherence.

Many coexisting factors must be considered in choosing the proportionsof ingredients in the dry niix= and the density of the solution for agiven draw.

These include, for example, the type of metal,

- its thickness, surface condition, ductility and other physicalcharacteristics; the typeof dies, die tolerance or clearance and surfaceor finish; and the depth and complexity of the draw.

In general, for stock having a high polish or mirror finish and forstainless steels a very thin coating is required. Deep draws andresultant high pressures and temperatures usually indicate a higherborax to soap ratio than lighter draws and lower temperatures andpressures. Rough surface or heavy tooth stock requires a relativelythick coatin that the surface cavities of the stock as well as thesurface projections should be well coated. New dies or dies with closeclearance require a thinner film than older dies or dies with moreclearance. The thinnest coating consistent with proper lubrication isdesirable.

Accordingly, for the thinnest films, such as used for highly polished orstainless steels, the dry mix is used in an amount of about two ouncesper gallon of water. For the coarsest films, such as used for roughfinished stock, the dry mix may be used in an amount as high as thirtyounces per gallon. A few trials with any particular stock of steel orother metal in the particular dies to be used will demonstrate the filmthickness and soap to borax ratio that may be used for optimum resultsfor the particular metal and draw.

Having described in detail the nature of my activelubricatingingredients and how such ma.- terials function, it thereforebecomes convenient to list a few specific examples illustrative of myinvention, the percentages being given by weight:

Example 2 Per cent Palm oil soap 18 Borax 82 Example 3 Per cent Tallowsoap 24 Borax 76 Example 4 Per cent Tallow soap 10 Palm oil soap 6 Borax84 Examples Per cent Palm oil soap 20 Borax In some instances it isdesirable to use a relatively heavy film and yet a limited amount oflubricant. For example, on rough surface or heavy tooth porous stock, arelatively thick film is required in order to cover the sheet properlyand this film normally would be in excess of the requirements oflubricant. Again, where storage facilities or the particular locale atwhich the metal is to be stored is apt to be damp, extra precautions maybe taken to assure proper film tenacity. In either of such instances asmall amount of starch or a comparable binder may be added to the drymix. Any starch such as, for example, cornstarch, potato starch, wheatstarch, etc., or equivalent material may be used as a binder inasmuch asit serves only the mechanical function of retaining the lubricants inplace and itself does not operate as a lubricant. For example, thecombinedcoating may comprise the following dry mix by weight and isapplied in an aqueous solution in an amount of about one pound of thedry mix per gallon of water:

- Thus if the starch is used in a maximum of 8% and the soap in anamount of 25%, the amount of borax would be reduced to the lowestminimum limit of 67%, whereas if the starch were maintained at theminimum of 1% and the soap at a minimum of 15 the borax would be used inthe amount of 84% which is below the maximum of when no binder isemployed. In other words, when a binder is employed the concentration ofthe soap and borax is adjusted so as to account for the 1% to 8%concentration of starch. However, this adjustment is such that the soapand borax concentration is well within the broad ranges hereinbeforegiven and may be employed without starch. The coating is applied bydipping the metal in an aqueous solution and then drying the metal inair.

If the starch content is increased, the coating tends to become moreviscous but is heavy and tends to sag. If the starch content isdecreased, the adhesion of the coating is reduced. If the soap isincreased, a more satisfactory coating for short draws is providedbecause of the low meltin point. If the soap is decreased, the coatingis more satisfactory for longer draws as soap tends to break down andcarbonize under the resultant increased heat of longer draws.

By applying the coating promptly after production of the metal, a bettersurface for the combined protective and lubricating coating is providedso that the coating cannot only adhere better but can lubricate moreeffectively and uniformly. This may be due to the higher surfaceporosity of clean, raw, newly produced metal, to absence ofoxide films,and to the cleanliness of the fresh surface generally. In any event,best results are obtained by applying the coating at the mill promptlyupon completion of production of the final metal.

After coiling or stacking, it is desirable. to wrap the metal to protectit from mechanical abrasion and the like and other hazards of shipment.

Metal prepared in this manner is in exceptionally fine condition whenreceived at the forming plant and can be used without other lubricant asreceived. It can be stored for lon periods without deterioration ordamage or undesirable efiects on the lubricating action of the coating.

2. As an article of manufacture, a piece of blank metal stock forsubsequent forming operations coated with a permanent, self-adherent dryhomogeneous lubricating and protecting film, said film consistingessentially of the following ingredients by weight:

3. As an article of manufacture, a piece of blank metal stock forsubsequent forming operations coated with a permanent, self-adherent dryhomogeneous lubricating and protecting film,

said film consisting essentially of the following ingredients by weight:

The material, when applied, forms a perma nent self-adherent, dry,homogeneous, lubricating film which might be termed amorphous ormicro-crystalline and which also protects the metal to which it isapplied during shipment and during storage.

This coating works satisfactorily and efliciently in metal stamping,press forming, wire and die drawing, and fabricating, and otheroperations. The word forming as used in the appended claims is meant toinclude all such metal working operations and such others as arecurrently practiced;

In some cases alkali metal salts, phosphate and acid salts, or, forexample, boric acid, can be used instead of the borax but theiradvantages are not as great and they are slightly hygroscopic so thatpermanent and efiective adherence of the coating cannot be depended onas fully under all conditions of storage.

After forming the stock with the coating thereon, the stock can becleaned readily by washing in hot water as all of the lubricatingingredients are water-soluble. Thus the very dificult and expensivesteps of removing the oil and grease residues of conventional oil andgrease lubricants are eliminated.

By the term consisting essentially of as used herein in defining thecoating composition or film, it is meant to define a composition or filmcontaining the claimed ingredients, in the relative proportions statedas the possible and actual constituents of the composition or film, butit is not meant to exclude the presence of minor amounts of conventionalcompounds or ingredients, the use of which is common practice in thelubrication of metals during forming operations.

This application is a continuation-in-part of my application Serial No.625,113, filed October 27, 1945, now abandoned.

Having thus described my invention, I claim:

1. As an article of manufacture, a piece of blank metal stock forsubsequent forming operations coated with a permanent, self-adherent dryhomogeneous lubricating and protecting film, said film consistingessentially of the following ingredients by weight:

7 Per cent Water-soluble high titre palm oil soap 10 to 33 Borax 90 to67 4. As an article of manufacture, a piece of blank metal stock forsubsequent forming operations coated with a permanent, self-adherent dryhomogeneous lubricating and protecting film, said film consistingessentially of the following ingredients by weight:

Per cent Water-soluble high titre soap having a melting point of from 36to 42 15 to 20 Borax to 80 5. A coating material for admixture withwater for coating 9. piece of blank metal stock and forming thereon apermanent, self-adherent dry homogeneous lubricating and protecting filmconsisting essentially of the following ingredients by weight:

Per cent Water-soluble high titre soap having a melting point of fromabout 36 to 42 10 to 33 Borax to 67 7. As an article of manufacture, apiece of blank metal stock for subsequent forming operations coated witha permanent, self-adherent dry homogeneous lubricating and protectingfilm, said film consisting essentially of the following ingredients byweight:

Per cent Starch 1 to 8 Water-soluble high titre soap having a.

melting point of from 36 to 42 15 to 25 Borax 84 to 67 8. A coatingmaterial for admixture with water for coating a piece of blank metalstock and forming thereon a permanent, self-adherent dry homogeneouslubricating and protecting film consisting essentially of the followingingredients by weight:

Per cent Starch 1 to 8 Water-soluble high titre soap having a meltingpoint of from 36 to 42 15 to 25 Borax 8% to 6? 9. As an article ofmanufacture, a piece of blank metal stock for subsequent formingoperations coated with a permanent, self-adherent dry homogeneouslubricating and protecting film, said film consisting essentially of thefollowing ingredients, by weight:

Per cent Cornstarch lto 8 Water soluble tallow soap 15 to 25 Borax 84 to67 10. As an article of manufacture, a piece of blank metal stock forsubsequent forming operations coated with a permanent, self-adherent dryhomogeneous lubricating and protecting film, said film consistingessentially of the following ingredients, by weight:

Per cent Cornstarch about Water soluble tallow soap about 25 Borax '70Per cent Cornstarch about 5 Water soluble tallow soap about 25 Borax '7012. As an article of manufacture, a piece of blank metal stock forsubsequent forming operations coated with a permanent, self-adherent dryhomogeneous lubricating and protecting film, said film consistingessentially of the following ingredients, by weight:

Per cent Starch lto 8 Water soluble tallow soap to i Borax 84 to 67 13.A coating material for admixture with water for coating a piece of blankmetal stock and forming thereon a permanent, self-adherent dryhomogeneous lubricating and protecting film consisting essentially ofthe following ingredients, by weight:

Per cent Starch 1to 8 Water soluble tallow soap 15 to 25 Borax .lBalance 14. A coating material for admixture with water for coating apiece of blank metal stock and forming thereon a permanent,self-adherent dry homogeneous lubricating and protecting film consistingessentially of the following ingredients by weight:

Per cent Mixture of water-soluble high titre tallow soap and watersoluble high titre palm oil soap, totaling 10-33 Borax -67 15. As anarticle of manufacture, a piece of blank metal stock for subsequentforming operations coated with a permanent, self-adherent dryhomogeneous lubricating and protecting film, said film consistingessentially of the following ingredients by weight:

' Per cent Mixture of water-soluble high titre tallow soap and watersoluble high titre palm oil soap, totaling 1033 Borax 90-67 16. Acoating material for admixture with water for coating a piece of blankmetal stock and forming thereon a permanent, self-adherent dryhomogeneous lubricating and protecting film consisting essentially ofthe following ingredients by weight:

Per cent Water-soluble high titre tallow soap 10-33 Borax 90 67 17. Acoating material for admixture with water for coating a piece of blankmetal stock and forming thereon a permanent, self-adherent dryhomogeneous lubricating and protecting film consisting essentially ofthe following ingredients by weight:

Per cent Water-soluble high titre palm oil soap 10-33 Borax 90-67 ROLANDA. WHITBECK.

No references cited

